The present invention relates to an automatic original feeding device adapted to be positioned in a copying machine, and the like. More particularly the present invention relates to an automatic original feeding device capable of detecting whether a plurality of originals have been mistakenly fed together in an overlapped state and are thus inhibiting an original feeding operation. If the overlapped state of the originals is detected, the jamming of the originals is avoided.
As shown in FIG. 1, a conventional automatic original feeding device used in copying machines and the like comprises an accommodation unit 2 for accommodating a plurality of original sheets 1 in a stacked state, an original feed loader 4 for feeding the originals 1 one by one from the accommodation unit 2 to a reading unit 3 on which an image on the original is read in response to a data reading command, and an original discharge loader 5 for discharging the original 1 whose image has been read at the reading unit 3.
A detection switch 6 is provided with the accommodation unit 2 to detect the presence of the originals in the accommodation unit 2. A detection switch 7 is provided with the original feed loader 4 to determine the amount of feeding required for locating the whole original 1 at the reading unit 3. In other words, by detecting a leading edge or a trailing edge of the original 1 by the detection switch 7, it becomes possible to determine the amount of feeding required for locating the whole original 1 at the reading unit 3, in accordance with the feeding speed of the original 1 as well as the distance from the detection switch 7 to the reading unit 3. Further, a detection switch 8 is provided with the original discharge loader 5 to detect whether the original 1 is completely discharged from the reading unit 3.
Next, a feeding operation executed by the conventional device arranged as described above will be described with reference to a flowchart shown in FIG. 2.
First, in step S1, when the detection switch 6 detects that at least one original 1 is contained in the accommodation unit 2, (i.e., the detection switch 6 is turned on), a pulse motor (not shown) is rotated by a predetermined amount in step S2 to cause the original 1 to be fed to the original feed loader 4. The original 1 is then fed to the reading unit 3 by the rotation of the original feed loader 4.
Thereafter, in step S4, it is determined whether the detection switch 7 is turned off or not. When it is determined that the detection switch 7 is turned off, (i.e., after the trailing edge of the original is passed through the position at which the detection switch 7 is located), the flow goes to step 5, where the original 1 is completely fed into the reading unit 3 by driving the original feed loader 4 by another predetermined amount of feeding.
When the original 1 has been fed into the reading unit 3, a scanner (not shown) is operated to read the image on the original 1 in step S6. When the image on the original 1 has been read, the pulse motor (not shown) is driven to discharge the read original 1 by the original discharge loader 5 in step S7.
Thereafter, the flow goes to step S8, where it is determined whether the detection switch 8 is turned off. When it is determined that the detection switch 8 is turned off, (i.e., the trailing edge of the original 1 is passed through the position at which the detection switch 8 is located), the pulse motor is rotated, in step S9, and the whole original 1 is completely led to the desired position, for example, at which a discharge tray is provided. In other words, it is possible to determine an amount of feeding required for feeding the whole original 1 to the desired position by detecting the passing of the trailing edge of the original 1 through the position at which the detection switch 8 is located.
Nevertheless, in the above arranged conventional automatic original feeding device, since the pulse motor is driven to feed the original toward the reading unit 3 when the detection switch 6 detects the presence of the original 1, a new original is fed to the reading unit 3 from the accommodation unit 2 in response to a feeding command even if an original sheet has been mistakenly fed to the position of the detection switch 7 by means of, for example, an undesirable vibration of the accommodation unit 2 or the like. Thus, the originals may be fed together in an overlapped state into the reading unit 3, and further, the next original is fed into the reading unit 3 regardless of whether the plurality of originals fed together still remain at the reading unit 3. This often causes jams of the originals.